The structure of small electrical appliances such as flashlight and electrical shaver usually was designed for chargeable. In general, there are two methods of charging: one is by means of the power cable, the other is directly by charging plug installed in electrical appliances. The former needs to set a voltage-transforming device in the end of plug, the size of which is bigger and more copper wire has been use; the same problems as the latter, to sum up, the current chargeable electrical device sizes are larger and the costs are higher.